It is now well known that some NMR properties of tumor tissues are different from the corresponding normal tissues. In this study it is being determined whether continuous wave NMR techniques can be used to distinguish between normal and tumor tissues. Relaxation times and linewidths are being measured. Both samples of single tissues and mixtures of normal and tumor tissues are being studied. The factors affecting the NMR relaxation times of water protons in tissues are being investigated. Analyses of the chemical compositions of the tissues are being carried out. A detailed model describing the properties of water in tumor and normal tissues is being developed. BIBLIOGRAPHIC REFERENCES: "Proton Magnetic Resonance Studies of Water in Tumor and Normal Tissues," R.E. Block and G.P. Maxwell, J. Magnetic Resonance, 14, 329 (1974); "Proton Magnetic Resonance Characteristics of Tissues: High Resolution Studies of Water and Lipid Signals from Normal and Tumor Rat Tissues." R.E. Block, Chapter 10 in "NMR in Cancer" ed. R. Damadian, Pacific Publishers, in press (1975).